New bike build what length to cut steerer

steve77345
steve77345 Posts: 52
edited July 2020 in Workshop
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Comments

  • ugo.santalucia
    ugo.santalucia Posts: 28,325
    Build the bike, then cut to length as required when you have found the correct position for you... in the meantime use spacers
    left the forum March 2023
  • sturmey
    sturmey Posts: 964
    Current bike head tube is 4 cm longer than new frame
    Obvious question- why have you bought a frame with a head tube 4cm shorter?

    Was the old bike way too tall?
    Or is this going to be a time trial bike hence the much lower front end.
    Just hope you aren't going to try and replicate the same front end height as the old frame using spacers.That would be wrong on so many levels.
  • steve77345
    steve77345 Posts: 52
    Hi,
    The old bike I felt was too large so have stepped down a size but didn't expect the head tube size to differ so much, geometry is very different too. Is adding that many spacers and testing really the best way to determine steerer length?
    Steve
  • sturmey
    sturmey Posts: 964
    You should work to the principle that 3 x 10mm spacers(or 4 at most) is the maximum you should use between frame and stem. Any more than this is not desirable. If you are unsure cut the steerer to take 40mm of spacers and work down from there.Otherwise you may want to reconsider whether the frame is the right size for you.
  • steve77345
    steve77345 Posts: 52
    Thanks.
    Farme is the right size, I had a test before purchase, just want to make sure I cut right.
    Steve
  • skelkelly
    skelkelly Posts: 80
    Find out how many spacers were on the one you tested...
  • sturmey
    sturmey Posts: 964
    Correct me if am wrong but I suspect your original question was actually more to do with the method of cutting the fork steerer to the correct length rather than a 'bike fit' related question.

    In which case, some relevant help here:

    http://www.parktool.com/blog/repair-hel ... and-sizing
  • steve77345
    steve77345 Posts: 52
    No cutting the steerer won't be a problem, my problem is working out the length to cut it.
    Email off to planet x to see if they can tell their set up on demo bike.
    Any other ideas?
    Steve
  • Velonutter
    Velonutter Posts: 2,437
    sturmey wrote:
    You should work to the principle that 3 x 10mm spacers(or 4 at most) is the maximum you should use between frame and stem. Any more than this is not desirable. If you are unsure cut the steerer to take 40mm of spacers and work down from there.Otherwise you may want to reconsider whether the frame is the right size for you.

    ^ What he said
  • nferrar
    nferrar Posts: 2,511
    Yeah leave it uncut and use a stack of spacers to get the initial position sorted but as above if you end up needing more than about 40mm of spacers then you've bought the wrong frame or need to slip your stem etc. If you do get a good position with a sensible amount of spacers under the stem then it comes down to a question of aesthetics vs resale. Ideally you want to cut it down so you have no spacers over the top of the stem but some people leave it uncut and have spacers above and below so it's a bit easier to sell on later as the new owner has more adjustment - it looks pretty ugly though IMO.

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